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American Journal of Respiratory and Critical Care Medicine Vol 176. pp. 1054-1055, (2007)
© 2007 American Thoracic Society

Correspondence

Blood Pressure and OSAS in Children

To the Editor:

We read with interest the pulmonary perspective by Drs. Ievers-Landis and Redline (1). This article cited two studies purporting to show that children with obstructive sleep apnea syndrome (OSAS) had higher blood pressure (BP) when, in fact, one of the studies cited (by Amin and coworkers) reported lower BP in children with an apnea–hypopnea index (AHI) > 5. (See Reference 14 in the article by Ievers-Landis and Redline [1].) Similar results were reported by Guilleminault and coworkers (2). Amin and coworkers (as cited above) attributed the low BP to BP dysregulation in the high AHI group while Guilleminault and coworkers (2) demonstrated increased vagal discharge as the cause of hypotension in those with obstructive sleep apnea (OSA). Nevertheless, we recently reported (3) that those with an AHI > 5 did indeed have higher wake systolic blood pressure (SBP), sleep SBP, and diastolic blood pressure (DBP). Obese children with an AHI > 5 had significantly higher prevalence of hypertension than obese children with an AHI ≤ 5 (odds ratio [OR], 6.667; 95% confidence interval [CI], 1.004–44.284), although this relationship was not found in nonobese children. We previously reported a meta-analysis (4) on the relationship between prevalence of hypertension and AHI and found an increased OR for hypertension in those with AHI > 1.0 (combined OR, 2.93). The meta-analysis was updated with the new data (3), and the combined OR was 4.04 (95% CI, 2.26–7.21) (Figure 1).


Figure 1
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  		Figure 1. Meta-analysis of hypertension and high apnea-hypopnea index (AHI) in children using a random-effect model.

 
Ievers-Landis and Redline quoted a study by Wing and coworkers (5) demonstrating that obesity may exert a greater impact (OR, 9.93) on the prevalence of OSA in Chinese children than in the Caucasian population. However, a much lower risk (OR, 2.03) was reported by us in Chinese children in Hong Kong when obese snorers were compared with nonobese snorers (6), and this result was similar to that reported in the Caucasian populations. These apparently conflicting results may reflect differences in the populations studied. All studies except that of Wing and coworkers (5) included patients referred to a sleep laboratory, and Wing and coworkers' study compared obese children attending the obesity clinic with nonobese community controls. Hence, there is currently insufficient evidence to support the statement that "Chinese children may be more susceptible to the effects of overweight than children of other ethnic groups."

It is important to realize that OSAS may affect the blood pressure in both directions in children. For pediatricians, the deleterious triad of OSAS, hypertension, and obesity should be appreciated. Further studies are required to quantify the impact of sleep-disordered breathing, not just OSAS, in children.

Daniel K. Ng, Lettie C. Leung, Ka-li Kwok and Chung-hong Chan

Kwong Wah Hospital
Hong Kong, China

FOOTNOTES

Conflict of Interest Statement: None of the authors has a financial relationship with a commercial entity that has an interest in the subject of this manuscript.

REFERENCES

  1. Ievers-Landis CE, Redline S. Pediatric sleep apnea: implications of the epidemic of childhood overweight. Am J Respir Crit Care Med 2007;175:436–441.[Abstract/Free Full Text]
  2. Guilleminault C, Kharmsov A, Stoohs RA, Kushida C, Pelayo R, Kreutzer ML, Chowdhuri S. Abnormal blood pressure in prepubertal children with sleep-disordered breathing. Pediatr Res 2004;55:76–84.[Medline]
  3. Leung LCK, Ng DK, Lau MW, Chan C, Kwok K, Chow P, Cheung JMY. Twenty-four-hour ambulatory BP in snoring children with obstructive sleep apnea syndrome. Chest 2006;130:1009–1017.[CrossRef][Medline]
  4. Ng DK, Chan C, Chow AS, Chow P, Kwok K. Childhood sleep-disordered breathing and its implications for cardiac and vascular diseases. J Paediatr Child Health 2005;41:640–646.[CrossRef][Medline]
  5. Wing YK, Hui SH, Pak WM, Ho CK, Cheung A, Li AM, Fok TF. A controlled study of sleep related disordered breathing in obese children. Arch Dis Child 2003;88:1043–1047.[Abstract/Free Full Text]
  6. Lam Y, Chan EYT, Ng DK, Chan C, Cheung J, Leung S, Chow P, Kwok K. The correlation among obesity, apnea-hypopnea index, and tonsil size in children. Chest 2006;130:1751–1756.[CrossRef][Medline]




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